The present invention relates to a semiconductor device; and, more particularly, to a method for manufacturing a copper interconnection provided with double diffusion barrier layers which are formed before and after a formation of the copper interconnection respectively, thereby preventing the diffusion of copper atoms effectively.
With a high integration of a semiconductor device, a copper interconnection is being applied to the device due to its low electrical resistance property. For employing the copper interconnection in the semiconductor device, a damascene process is used because dry-etching process cannot be applied directly to deposit a copper interconnection layer in a damascene pattern.
Referring to FIGS. 1A to 1D, there are provided cross sectional views setting forth a conventional method for manufacturing the copper interconnection by using a damascene process.
The manufacturing steps begin with a preparation of active matrix 110 provided with a substrate 110, an insulating layer 112 and a contact region 111. The insulating layer 112, is formed on top of the substrate 110 and then patterned into a predetermined configuration by using a damascene process, thereby obtaining a shallow opening 116 for a metal interconnection and a deep opening for a contact. Thereafter, a diffusion barrier layer 114 is formed on entire surface including the openings 116, 118 and the insulating layer 112 for preventing a penetration of copper atoms into the insulating layer 112. The diffusion barrier layer is made of a material such as TiSiN, Ta, TaN, WSiN, WN or the like.
In a next step as shown in FIG. 1B, a first copper layer 120 is formed on the diffusion barrier layer 114 by using a method such as a physical vapor deposition (PVD) technique at a room temperature.
In a subsequent step as shown in FIG. 1C, a second copper layer is formed on the first copper layer 120 for reflowing the copper atoms into the openings 116, 118 by using the PVD technique at a high temperature.
Finally, a copper layer is polished back to a top surface of the insulating layer 112, thereby obtaining a copper interconnection 124 being remained within the openings 116, 118 and a diffusion barrier 114A as shown in FIG. ID. Here, polishing back of the copper layers 120, 122 and the diffusion barrier layer 114 is accomplished by a chemical mechanical polishing (CMP) technique.
In the conventional method for manufacturing the copper interconnection, a single diffusion barrier layer, e.g., TiSiN, Ta, WSiN, WN or the like, is employed. However, in case that there are defects in the single diffusion barrier layer, the copper atoms may diffuse through these defects that a characteristic of the semiconductor device is deteriorated eventually.
It is, therefore, an object of the present invention to provide a method for manufacturing a copper interconnection provided with a double barrier layer, thereby preventing the diffusion of copper atoms effectively.
In accordance with one aspect of the present invention, there is provided a method for manufacturing a copper interconnection, the method comprising the steps of: a) preparing an active matrix provided with a substrate, an insulating layer and an opening formed with a predetermined shape through the insulating layer; b) forming a first aluminum oxide layer on surfaces of the opening and the insulating layer; c) forming a first conductive barrier layer on the first aluminum oxide layer; d) forming a copper layer into the opening and on the first conductive barrier layer; e) polishing back the copper layer to a top surface of the insulating layer, thereby obtaining a copper interconnection within the opening and a first double diffusion barrier layer provided with the first aluminum oxide layer and the first conductive barrier layer; and f) forming a second diffusion barrier layer on the copper interconnection and the insulating layer.